In 1972, the state of Texas began electing members of the state House of Representatives and State Senate, for the first time, by single-member districts. Washington, along with four other minority candidates, Anthony Hall, George T. "Mickey" Leland, Benny Reyes and Cecil Bush, (dubbed the "People's Five"), ran for seats in the Texas House of Representatives. Washington was elected, and represented District 86 in the state House from 1973 to 1982. He then represented District 13 in the state senate from 1983 until 1989.

In March, 1994, Washington was routed in the Democratic primary by Houston City Councilwoman Sheila Jackson Lee, winning only 36.5 percent of the vote. Lee won in November and still holds the seat today.

On New Year's Day 2008, Washington shot at a car containing two teenagers.[2] After being indicted by a grand jury in 2009, he agreed to two years of probation.[2] However, Washington's attorney subsequently claimed that Washington fired because his life was in danger.[2] Washington has since countersued the teenagers, alleging assault and property damage.[3]

On January 8, 2015, Washington received a suspension of his Texas attorney's license. The 335th District Court of Bastrop County, Texas found that Washington had violated various rules, including the rules prohibiting neglecting a legal matter entrusted to him and failing to keep a client reasonably informed. On March 12, 2015, a "modified judgment was entered imposing a four-year partially probated suspension with 12 months active." He was also ordered to pay over $24,600 in legal fees and expenses. Washington filed an appeal.[5]